Performance of a Full-Duplex System in Non-Linear and Time-Varying Self-Interference Channel

The main challenge in full-duplex transceiver design is the self-interference (SI). Analog SI isolation is performed at radio frequency (RF) signal by using an antenna design based on the characteristic modes theory and using active cancelation processing. The RF canceler is tuned using an automatic gain control (AGC) enhanced variable-step steepest descent algorithm while transmitting a data signal. The inclusion of a non-linear power amplifier does not affect the tuning performance, when realistic adjacent channel power ratio cases are considered. However, the changes in the SI channel can have a major impact on the full-duplex link due to need to re-tune the canceler repeatedly.